Absolutely no problem with this.
It's only banter. I imagine every single English side who goes to Cardiff or Swansea sing it. It's not a Boro 'thing' because they are racist or knuckle draggers
. If the 'worst' thing at football is English fans singing the national anthem then we'd take that.
I also must stress the the majority of Welsh and Scottish have far more 'issues' with us than we do with them.
The way things are going at football is basically like going to the cinema. Please don't irradicate all 'banter' and passion. I really don't want to only sit and sing 'come on Boro' and not interact with the other fans.
That said I'm not keen on being called a peado whenever we play Sunderland (the only side who hammer us for it). That's 'offensive'.